The present invention relates to a fluid mixer capable of performing a process of mixing and chemical reactions of fluid such as liquid or gas on a scale of less than 1 mm in width of a flow path.
In recent years, in a chemical synthesis or chemical analysis field, fluid mixers have been used which are made up of a flow path of several tens to several hundred μm manufactured by microfabrication technology with the aim of shortening time for mixing and reactions. The fluid mixers of this kind are called micro mixers or micro reactors.
The micro mixer has a short characteristic length of a flow path and a small Reynolds number which is a non-dimensional number indicating a ratio between inertial force and viscous force in a fluid and, therefore, flow becomes a layer stream. As a result, when various kinds of fluids are mixed, the mixing progresses mainly by molecular dispersion. By shortening a characteristic length of a flow path, dispersion distance is reduced, which enables rapid mixing and highly efficient chemical reactions.
EP 1762298 A1 discloses a micro reactor in which a plurality of nozzles for two different fluids are arranged on a circumference to form multilayer streams of which the two fluids alternately flow and widths of the multilayer streams are reduced towards downstream, namely, a center of the reactor.
By using the micro reactor having such characteristics as described above, production of homogeneous particles by reactions between fluids has been attempted.
U.S. Pat. No. 7,579,191 discloses a structure in which fluid not contributory to reactions is placed between an internal wall of a micro reactor and a reaction fluid to produce particles.
U.S Patent Publication No. 2007-0291581 discloses a structure in which a check-valve is provided between an introducing flow path of a reaction fluid and a portion for fluid joining and mixing.
Purposes to produce particles by using a micro reactor are various but one of the purposes is to produce high-quality particles by uniformly controlling conditions for reactions for producing particles to rapidly mix a plurality of fluids.
In the micro reactor disclosed in EP 1762298 A1, rapid mixing is achieved by gradually narrowing flow paths configured to mix fluids, however, this micro reactor has a problem in that clogging easily occurs due to produced particles in the portion where the fluid-mixing flow paths are gradually narrowed.
Also, the micro reactor disclosed in U.S. Pat. No. 7,579,191 has also a problem in that, though adhesion of produced particles can be suppressed, due to mixing of fluids not contributory to reactions, control on uniform reactions is difficult.
Additionally, the micro reactors disclosed in U.S. Pat. No. 7,579,191 and U.S Patent Publication No. 2007-0291581 are configured to perform mixing by reducing a characteristic length of the flow paths for mixing fluids, a shape to be divided and/or dimensions to shorten a mixing distance. Therefore, there is also a problem that mixing efficiency depends on dimensions of the flow path and the improvement of mixing speed without being limited by dimensions of the flow path is difficult.